* {
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    min-height: 100vh;
    overflow: hidden;
    justify-content: center;
    align-items: center;
    background: #010b10;
}

svg {
    width: 0;
    height: 0;
}

.loading {
    width: 200px;
    height: 200px;
    position: relative;
    filter: url(#gooey);
}

.loading span {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: block;
    animation: loading 4s ease-in-out infinite;
    /* var函数用来插入css变量的值，css变量名称以--开头 */
    animation-delay: calc(0.2s * var(--i));
}

.loading span::before {
    content: '';
    position: absolute;
    top: 0;
    left: calc(50% - 20px);
    width: 40px;
    height: 40px;
    background: linear-gradient(#fce4ec, #03a9f4);
    border-radius: 50%;
    box-shadow: 0 0 30px #03a9f4;
}

@keyframes loading {
    0% {
        transform: rotate(0deg);
    }

    50%,
    100% {
        transform: rotate(360deg);
    }
}